Topic: Issues With Xbox Power (Read 159 times)

daytona · « **on:** January 24, 2006, 12:22:00 AM »

hey guys update, I tried switching the front circuit board with the buttons and still the same issue. do you think the power supply needs replacement?

thx

mikeymikeuk · « **Reply #1 on:** January 24, 2006, 03:32:00 AM »

It may do. If you've got a spare try it.

pablot · « **Reply #2 on:** January 24, 2006, 04:17:00 AM »

follow this little tutorial to sort that out. Helps out most of the time.

http://pablot.com/in...xbox&submenu=pe

regards
Pablot

pablot · « **Reply #3 on:** January 24, 2006, 02:05:00 PM »

yes, set the multimeter to 20k, and yes, the screw can be used for ground

pablot · « **Reply #4 on:** January 24, 2006, 03:12:00 PM »

uhm sorry?

you are supposed to measure the resistors in the yellow box for resistance, set the multimeter to 20k ohms. They should be "arroun" 10k.

Then measure the continuity of the purple and cyan traces with a multimeter. If you don't have a continuity position on your multimeter then measure the resistance. Put the multimeter on like 200 ohms and the continuity points should have arround 0 ohms between them.

pablot · « **Reply #5 on:** January 24, 2006, 04:12:00 PM »

no, lets try again.

Those small black rectangular things, they are resistors. You mesure the resistance over them by placeing the probes of the oscilloscope on each side of them (make sure they are touching metal).

If they were fine (arround 10k) then you have to see if the connection between those resistors and the pic mcu at the back of the mobo is intact. You do that by setting the multimeter to 200 ohms and measure from one side of the purple trace (up by the resistors) to the other side (on the legs of the PIC mcu). And you want the result to be arroun 0 ohms.

if one of the above steps failed then come back here and post, other wise I don't know what is wrong.

spyman · « **Reply #6 on:** January 24, 2006, 08:40:00 PM »

I purchased the unit off him earlier tonight before I knew that he actually knew more about the problem.

Anyways here are the results from the tests I've done.

the 10k ohm resistors all measure 10K ohm, I changed 2 of them that read 4.7k ohm (two in the very front, however when they were not both connected they read 9k ohm each approx. So after I changed it they now read 5.7 ohm each , but when not connected they are 10k ohm.

The version of the unit is a 1.1, on my 1.0 mobo all 4 show up as 10k ohm (this is where I took the extra resistors).

So that is the odd part I am finding. Unfortunately I can't get any of our technicians to look at this for quite some time so I would need to do this myself. I've got a fair bit of knowledge with electronics ( engineering electronics 201) but its been a long while, so you may need to bare with me.

The purple trace and pic mcu = 01.0 ohm

The system starts up without the pcb connected so its the mobo, but cant figure out what.
the board is very clean, and I don't see an corrosion. I cleaned it again just in case, but no dice.

pablot · « **Reply #7 on:** January 25, 2006, 01:32:00 AM »

can you take some photos of the resistor area?

sounds like you have a short of some kind between the eject line an the power line since the reistors seem to measure like they are connected in parallel.

pablot · « **Reply #8 on:** January 25, 2006, 02:00:00 PM »

well.. hard to tell what is wrong..
measure the voltage (relative to ground) that you get on the purple trace when the xbox is connected to power

pablot · « **Reply #9 on:** January 25, 2006, 04:20:00 PM »

no, its supposed to measure 3.3V, so either those pull-up resistors aren't doing what they are supposed to or you have a short to ground that is pulling it to ground..

Inspect everything again and make sure there are no shorts, my current guess stands at that there is a short to ground somewhere..

measure the voltage on both sides of R3G3 (or whatever its called on your mobo)

http://pablot.com/pics/pe_trace.jpg

pablot · « **Reply #10 on:** January 27, 2006, 01:55:00 AM »

don't think its been mentioned, so what version is the xbox?

spyman · « **Reply #11 on:** January 29, 2006, 02:50:00 PM »

Updates:

I decided to mod the console to see what would happen if I installed a dashboard and told it to power down from there. It does power down from the dashboard and it does remain off. When trying to turn it on using the "power" button it does not respond. When hitting the "eject" button it will power on.

Any ideas?

pablot · « **Reply #12 on:** January 29, 2006, 02:52:00 PM »

well.. its 100% certain that it is a problem with the power-on trace, question is exactly what the problem is and where it is located.. best thing would be for you to follow the trace all the way from the pin on the PIC-chip marked with purple down to the resistor it connects to and check all the surroundings..

measure the voltage on the pic leg marked with purple

spyman · « **Reply #13 on:** February 02, 2006, 08:33:00 AM »

Thanks for the help thus far, unfortunately my time ran out and my impatient customer wanted to buy it even with the problem. I had recently fixed one of his other xbox systems, but informed him hard modding it would not be wise, so he wanted this one I had :-/ I really wanted to figure it out, because I have done a various amount of repairs on systems, but this is the first on an unmodded unit with this problem. My tech is back tomorrow so worst case I could have got him to deal with it, but all is good anyways.

Thanks again for all the help

Cheers,
Al

Author Topic: Issues With Xbox Power (Read 159 times)